In an email, NOAA/GLERL scientist George Leshkevich tells us that satellite imagery also indicates "that ice cover is starting to break up on the Great Lakes."

Lake Michigan, though, can lay claim to a new record, at least in terms of what's in the data from recent decades. Its ice cover peaked at 93.3 percent on Saturday. Leshkevich says the lake's previous record, 93.1 percent, was set in 1977. The researchers at NOAA/GLERL began collecting the data in 1973.

By the way, Lake Michigan's ice caves haven't been safe to visit for a few weeks. As the Detroit Free Press has reported, "milder temperatures and high winds have broken up the ice sheet on the lake side of the formations, and open water is visible near the caves."